Granular parakeratosis--a clinical-pathological correlation of 10 cases

Granular parakeratosis describes chronic skin lesions within the intertriginous areas that demonstrate microscopically parakeratosis together with retention of keratohyalin granules within a thickened stratum corneum. Granular parakeratosis is rarely diagnosed, since it is still relatively unknown within the differential diagnoses of intertriginous eruptions, and a skin biopsy is required for diagnosis. In order to gain insight into the clinical-histopathologic correlation, we present 10 cases of granular parakeratosis.

The files of the DermatoHistologisches Labor Dr. H. Laaff, Freiburg, were searched for the diagnosis of granular parakeratosis. Identified cases were evaluated for clinical information and histopathologic characteristics.

From 2004 to 2007 10 cases (7 women, 3 men) of granular parakeratosis were found corresponding to a frequency of 0.004%. The average age was 62 (33-82). In women lesions occurred in submammary region (4), axillae (2) and popliteal fossa; in men, groin (2) and genital region. Clinically two different patterns are recognized--lichen planus-like red-brown slightly hyperkeratotic or scaly papules, and larger plaques which are either bright red shiny or grey-brown with lichenification. Histologically the typical granular parakeratosis was seen in a prominently thickened stratum corneum. It remains unclear whether granular parakeratosis is a disease entity or whether it reflects a reaction pattern to unknown stimuli.